Zac Vawter, 31, is a software engineer who lost his right leg in a motorcycle accident three years ago. On Sunday, Vawter strapped on a bionic "smart limb" designed by the Rehabilitation Institute of Chicago and participated in an annual stair-climbing event called “Skyrise Chicago."

“Everything went great,” Vawter told the Washington Post after the event. “The prosthetic leg did its part, and I did my part.”

The neural-controlled prosthetic leg, which weighs about 10 pounds, is driven by Vawter's thoughts. When he pushes on the device to stand up, it reads his intent and triggers built-in motors, belts and chains to push back on him, propelling him up.

“With my standard prosthesis, I have to take every step with my good foot first and sort of lift or drag the prosthetic leg up," Vawter explained in a statement. "With the bionicleg, it’s simple, I take stairs like I used to, and can even take two at a time.”